22. (1) A person in authority who engages in a sexual act with a relevant person shall be guilty of an offence.

(2) A person in authority who invites, induces, counsels or incites a relevant person to engage in a sexual act shall be guilty of an offence.

(3) It shall be a defence to proceedings for an offence under this section for the defendant to prove that he or she was reasonably mistaken that, at the time of the alleged commission of the offence, the person against whom the offence is alleged to have been committed was not a relevant person.

(4) It shall not be a defence to proceedings for an offence under this section for the defendant to prove that the person against whom the offence is alleged to have been committed consented to the sexual act of which the offence consisted.

(5) F1[…]

(6) A person guilty of an offence under subsection (1) where the sexual act consisted of sexual intercourse, buggery or an act described in section 3(1) or 4(1) of the Act of 1990 shall be liable on conviction on indictment to imprisonment for a term not exceeding 10 years.

(7) A person guilty of an offence under subsection (1) where the sexual act consisted of an act which if done without consent would constitute a sexual assault, or an offence under subsection (2) shall be liable on conviction on indictment to imprisonment for a term not exceeding 5 years.

(8) In this section—

“person in authority”, in relation to a relevant person against whom an offence is alleged to have been committed, means any person who as part of a contract of service or a contract for services is, for the time being, responsible for the education, supervision, training, treatment, care or welfare of the relevant person;

“relevant person” means a person who has—

(a) a mental or intellectual disability, or

(b) a mental illness,

which is of such a nature or degree as to severely restrict the ability of the person to guard himself or herself against serious exploitation.